They stand for Doctor of Osteopathic Medicine, which is a professional degree of physicians and surgeons. It is a bit different than an M.D. in the sense that D.O.'s are taught physical manipulation,...
The CAT scan is computerized axial tomography. The words "axialized" and "tomographic" might be substituted in. A link can be found below. Oh, and we're moving away from that term now. It's just...